DIY Turbo Discussion greddy on a 1.8? homebrew kit?

The new Garrett G25-550 turbo

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Old 11-23-2020, 03:33 PM
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Old 11-24-2020, 02:57 PM
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Well I got the down pipe built. It was a pita and is super tight. You have to lift the engine up a bit to get it in and out due to the bends. Next one should be a little better and I have some ideas to get part of it custom bent. Rear shelf needs a good bit of the lip knocked back or cut out.
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Old 11-25-2020, 07:25 AM
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I literally can't wait
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Old 11-25-2020, 02:16 PM
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Old 11-25-2020, 04:36 PM
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I am hoping to head to the shop with the dyno I use this coming Monday to get some time on it. It will depend on their schedule, but I need to do some dyno testing naturally aspirated to get my engines baseline. Then I will get to jump into the G25. So it will probably be a bit. But I am super excited to see how this thing does, especially compared to a GTX.
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Old 11-25-2020, 04:52 PM
  #146  
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Originally Posted by shuiend
I am hoping to head to the shop with the dyno I use this coming Monday to get some time on it. It will depend on their schedule, but I need to do some dyno testing naturally aspirated to get my engines baseline. Then I will get to jump into the G25. So it will probably be a bit. But I am super excited to see how this thing does, especially compared to a GTX.
Here is what I'm most afraid of, the g25 destroying the gtx and me having to buy one lololol
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Old 11-25-2020, 05:38 PM
  #147  
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Originally Posted by andyfloyd
Here is what I'm most afraid of, the g25 destroying the gtx and me having to buy one lololol

Maybe. It will be interesting to see how spool compares. The G25 has the higher top end, so it may spool a bit slower. It is a bit sad it won't be a direct drop in replacement for the older t2 turbo's, but I think Garrett wanted to catch up to BW in design.

Also i very much hate that every turbo maker makes their 3" v-band outlets on the turbo different. Not being able to just use the same flange for everything sucks.
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Old 11-25-2020, 05:51 PM
  #148  
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Blue line is GTX2860R Gen2 @ 19-20psi, Yellow is 2560R @18-19psi
Originally Posted by shuiend
Maybe. It will be interesting to see how spool compares. The G25 has the higher top end, so it may spool a bit slower. It is a bit sad it won't be a direct drop in replacement for the older t2 turbo's, but I think Garrett wanted to catch up to BW in design.

Also i very much hate that every turbo maker makes their 3" v-band outlets on the turbo different. Not being able to just use the same flange for everything sucks.
Yes I feel like turbo companies are like bike companies ( mtb, road bikes) where they like to all do things a little differently. It would be super nice to have on standard on V band thats for sure. Here is my guess on the G25 vs the GTX. I think it will spool about 300-400rpm slower just because the compressor does flow more and the turbine is also higher flow so in theory it should spool slightly slower but support a bunch more up top. Whats the a/r on the turbine section you went with?

My GTX2860 vs my old GT2560 is interesting because it basically spools about the same. Even though the 2560 spools slightly sooner the power difference was pretty much zero, my thought is that the GTX being a lot more efficient makes up for the slightly slower spool with efficiency since there is less backpressure. The only spot where the 2560 beat out my 2860 was from like 2800-3300rpm and even there it was like splitting hairs. After 3300 the 2860 takes off and I was able to hit 22psi @ like 3700 rpm in 5th gear on a 6 speed with a 3.909 rear end. And this is using a FM manifold and turbine outlet. When I throw on my built head in the coming weeks Im gonna port the turbine outlet a LOT and use a 3" downpipe as Im currently still on a 2.5"DP. Really look9ing forward to your test and its about time someone did this. Cats aplenty for you!!
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Old 11-26-2020, 12:01 AM
  #149  
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At sea level, with a PR of 2.5 (~22psi) I expect the g25-550 and the gtx2860r g2 to spool almost exactly the same. The g25 may actually be a bit better due to improved hot side performance.
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Old 11-26-2020, 09:48 AM
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Originally Posted by Ted75zcar
At sea level, with a PR of 2.5 (~22psi) I expect the g25-550 and the gtx2860r g2 to spool almost exactly the same. The g25 may actually be a bit better due to improved hot side performance.
Well that would be pretty sweet if the G25 spools the same and then has the bigger top end,

I guess I should just go buy the 1bar and 1.5bar to go on this turbo, .5bar is what I currently have.

Really I need to get some more turbo sales so I can afford a BMW trans to swap in to hold all this power.
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Old 11-26-2020, 11:18 AM
  #151  
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Originally Posted by shuiend
Well that would be pretty sweet if the G25 spools the same and then has the bigger top end,

I guess I should just go buy the 1bar and 1.5bar to go on this turbo, .5bar is what I currently have.

Really I need to get some more turbo sales so I can afford a BMW trans to swap in to hold all this power.
Yeah, like the FM benchmarking between the 2560/2860...
If you don't push this to at least a PR of 2 with an increased rev limit, or more appropriately 2.5, the results are likely to be unremarkable.
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Old 11-26-2020, 07:40 PM
  #152  
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Originally Posted by Ted75zcar
Yeah, like the FM benchmarking between the 2560/2860...
If you don't push this to at least a PR of 2 with an increased rev limit, or more appropriately 2.5, the results are likely to be unremarkable.
Yea when FM compared the turbos they ran like 10psi or something crazy low like that. If you dont push the PR the new turbos arent gonna show their worth a 2560 and 2860 @10psi will be basically the same but the 2560 will beat it out on spool because of the tiny turbine wheel within. The GTX and G25 stuff wants you to push the PR so that the compressor wheel rpm is high where they can show their true worth. Heck, the GTX2860 Gen2 wheel is physically smaller than a GT2560R wheel by .50mm on the inducer and yet it flows 12lb more of air.
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Old 11-30-2020, 11:24 PM
  #153  
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Today was supposed to be dyno day, right? The suspense is killing me
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Old 12-01-2020, 07:08 AM
  #154  
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Originally Posted by dan91
Today was supposed to be dyno day, right? The suspense is killing me
No. I was going to try to go to to the dyno shop to ask about getting time. It did not happen. Mostly because they were not back from the holidays. I am hoping to get down to them today to talk and see if maybe some time next week or the week after.

I have a number of setups to dyno first before I try out the g25.
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Old 01-04-2021, 02:18 PM
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Turbozentrum in the UK/Germany have started selling a GTX28 drop in replacement of the G25......

Obviously going to retain a load of the GTX series limitations with the turbine housing and wastegate design, but interesting nonetheless.

https://turbozentrum.co.uk/Garrett-G...olt-On-Upgrade


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Old 01-04-2021, 04:18 PM
  #156  
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Oh my god, the world needs this SO bad, not only miatas
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Old 01-04-2021, 06:14 PM
  #157  
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Just to confirm, the T2 G25 housing with the 3" band on the exhaust side fits the kraken manifold, top and low mount, I can also offer downpipes for it and full exhaust. If you have a EFR downpipe the fitment is quite close, only issue is the Garrett vband which is a few mm smaller than the EFR vband, I machine universal 3" bands to fit the G25, save quite a bit on cost and seems to work well









And here is the low mount EFR downpipe


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Old 01-04-2021, 08:22 PM
  #158  
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Old 07-03-2023, 02:26 PM
  #159  
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